Receiver optical assembly and assembly method thereof

ABSTRACT

A receiver optical assembly includes: an optical platform, a receiver optical port and a wavelength division multiplexer being arranged along an optical path on the optical platform; a circuit board, a photodetector array being disposed on the circuit board; a mounting block, a focusing lens and an optical path shifter being disposed on t the mounting block, the mounting block being fixed on the circuit board, and the optical path shifter being placed above the photodetector array. Incident light containing a multi-channel optical signal enters through the receiver optical port, and the wavelength division multiplexer divides the incident light into a plurality of single-channel optical signal beams. The single-channel optical signal beams are coupled to photodetectors on the photodetector array after passing through the focusing lens and the optical path shifter on the mounting block.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims priority to Chinese PatentApplication 201811269497.1, filed on Oct. 29, 2018, the entire contentof which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to the field of optical communicationtechnology and, more particularly, to a receiver optical assembly andassembly method thereof.

BACKGROUND

As the market places increasingly higher demands on the volume ofinformation and the speed of information transmission, the transmissionspeed of optical communication products also increases. However, inorder to lower a device's capacitance so as to improve the performanceof its high frequency response, the effective light receiving area(photosensitive area) of a photodetector (photodiode), which is animportant component in a receiver optical assembly, is made increasinglysmaller. As the effective light receiving area of a photodetectorbecomes smaller, the light energy received needs to be more concentratedin order to effectively converge on a detector assembly, and, at thesame time, higher requirements are also imposed on the assemblytolerance of the device—the tighter the tolerance, the better. Thisimposes higher requirements on subsequent production and assembly.

SUMMARY

Purposes of the present disclosure include providing a receiver opticalassembly and assembly method thereof that feature high operability,convenient coupling, effectively improved assembly efficiency, andincreased degree of assembly tolerance.

In order to achieve one of the aforementioned purposes, one embodimentof the present disclosure provides a receiver optical assembly. Thereceiver optical assembly includes: an optical platform, a receiveroptical port and a wavelength division multiplexer being arranged alongan optical path on the optical platform; a circuit board, aphotodetector array being disposed on the circuit board; and a mountingblock, a focusing lens and an optical path shifter being disposed on themounting block, the mounting block being fixed on the circuit board, andthe optical path shifter being placed above the photodetector array.Incident light containing a multi-channel optical signal enters throughthe receiver optical port and the wavelength division multiplexerdivides the incident light into a plurality of single-channel opticalsignal beams. The single-channel optical signal beams are coupled tophotodetectors on the photodetector array after passing through thefocusing lens and the optical path shifter on the mounting block.

Another embodiment of the present disclosure provides an assembly methodfor a receiver optical assembly. The method includes: installing areceiver optical port and a wavelength division multiplexer on anoptical platform to form a first assembly; installing a photodetectorarray on a circuit board to form a second assembly; installing afocusing lens and an optical path shifter on a mounting block to form athird assembly; installing the first assembly and second assembly insidea housing; covering the photodetector array with the third assembly andadjusting the position of the third assembly so that an optical signaloutputted from the wavelength division multiplexer is coupled to thephotodetector array; and fixing the third assembly on the circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded-view diagram illustrating an optical module;

FIG. 2 is a structural diagram illustrating a receiver optical assemblyaccording to a first embodiment of the present disclosure;

FIG. 3 is an exploded-view diagram illustrating part of the structure inFIG. 2;

FIG. 4 is a diagram illustrating the installation of a focusing lens andan optical path shifter according to the first embodiment;

FIG. 5 is a structural diagram illustrating the focusing lens and theoptical path shifter in FIG. 4;

FIG. 6 is an exploded-view diagram illustrating a structure of areceiver optical assembly according to a second embodiment of thepresent disclosure;

FIG. 7 is a structural diagram illustrating a focal reducing lens arrayaccording to the second embodiment;

FIG. 8 is an exploded-view diagram illustrating a structure of areceiver optical assembly according to a third example embodiment of thepresent disclosure.

DETAILED DESCRIPTION

The text below provides a detailed description of the present disclosurewith reference to specific embodiments illustrated in the attacheddrawings. However, these embodiments do not limit the presentdisclosure; the scope of protection for the present disclosure coverschanges made to the structure, method, or function by persons havingordinary skill in the art on the basis of these embodiments.

In order to facilitate the presentation of the drawings in the presentdisclosure, the sizes of certain structures or portions have beenenlarged relative to other structures or portions; therefore, thedrawings in the present application are only for the purpose ofillustrating the basic structure of the subject matter of the presentapplication.

Additionally, terms in the text indicating relative spatial position,such as “upper,” “above,” “lower,” “below,” and so forth, are used forexplanatory purposes in describing the relationship between a unit orfeature depicted in a drawing with another unit or feature therein.Terms indicating relative spatial position may refer to positions otherthan those depicted in the drawings when a device is being used oroperated. For example, if a device shown in a drawing is flipped over, aunit which is described as being positioned “below” or “under” anotherunit or feature will be located “above” the other unit or feature.Therefore, the illustrative term “below” may include positions bothabove and below. A device may be oriented in other ways (rotated 90degrees or facing another direction), and descriptive terms that appearin the text and are related to space should be interpreted accordingly.When a component or layer is said to be “above” another part or layer or“connected to” another part or layer, it may be directly above the otherpart or layer or directly connected to the other part or layer, or theremay be an intermediate component or layer.

FIG. 1 is an exploded-view diagram illustrating an optical module 1. Asillustrated in FIG. 1, an optical module 1 generally includes a housing10 and an optical assembly 20 disposed inside the housing 10. Thepresent disclosure provides a solution for a receiver optical assemblyat a receiving end of the optical assembly 20 inside the optical module1.

Example Embodiment 1

FIG. 2 is a structural diagram illustrating a receiver optical assembly100 according to a first embodiment of the present disclosure. FIG. 3 isan exploded-view diagram illustrating part of the structure in FIG. 2.FIG. 4 is a diagram illustrating an installation of a focusing lens andan optical path shifter according to the first embodiment. FIG. 5 is astructural diagram illustrating the focusing lens and the optical pathshifter in FIG. 4. As illustrated in FIGS. 2 through 5, the receiveroptical assembly 100 in this example embodiment includes, arranged alongan optical path, a receiver optical port 212, a wavelength divisionmultiplexer 213, a focusing lens 232, an optical path shifter 233, and aphotodetector array 222, as well as a circuit board 221. Here, thereceiver optical port 212 and the wavelength division multiplexer 213are disposed on an optical platform 211, forming a first assembly 21;the photodetector array 222 is disposed on the circuit board 221,forming a second assembly 22; the focusing lens 232 and the optical pathshifter 233 are disposed on a mounting block 231, forming a thirdassembly 23. In this example embodiment, the focusing lens 232 isdisposed on the optical path before the optical path shifter 233. Inanother example embodiment, the focusing lens 232 may also be disposedon the optical path after the optical path shifter 233. Theaforementioned mounting block 231 is fixed on the circuit board 221,placing the optical path shifter 233 above the photodetector array 222.

In this example embodiment, the mounting block 231 includes a supportingportion 231 a. The mounting block 231 is fixed on the circuit board 221by means of its supporting portion 231 a to provide a clearance spacethat prevents the focusing lens 232 and the optical path shifter 233from pressing down on the photodetector array 222 or other componentsbelow, and, at the same time, to form a coupling gap between thefocusing lens 232 and the photodetector array 222. Here, the supportingportion 231 a may have various shapes, e.g., a column shape or a frameshape, etc. The supporting portion 231 a and the circuit board 221 maybe fixed and connected by means of an adhesive, etc. When being coupled,front and back portions of the optical path are coupled by means ofadjusting the position of the mounting block 231. When the position ofthe mounting block 231 is adjusted to an optimal coupling position, anadhesive layer may be used to conveniently fill in a space between abottom of the supporting portion 231 a of the mounting block 231 and thecircuit board 221 so as to fix the mounting block 231 at the optimalcoupling position.

During operation, incident light containing a multi-channel opticalsignal enters, through the aforementioned receiver optical port 212, thewavelength division multiplexer 213, which divides the incident lightinto a plurality of single-channel optical signal beams. Thesingle-channel optical signal beams are then respectively coupled tophotodetectors on the photodetector array 222 after passing through thefocusing lens 232 and the optical path shifter 233 on the mounting block231. In the present embodiment, the focusing lens 232 and the opticalpath shifter 233 are integrated to form an assembly, and the front andback portions of the optical path are coupled by means of adjusting thisassembly, thus effectively improving coupling efficiency. At the sametime, the mounting block 231 is added so that the position of theaforementioned assembly is conveniently adjusted by means of graspingthe mounting block 231, thus increasing the operability of the couplingand assembly and effectively improving assembly efficiency.

As illustrated in FIGS. 3 through 5, in this example embodiment, thefocusing lens 232 uses a structure formed by a plurality of couplinglenses 232 a that are each positioned along the optical path of itsrespective single-channel optical signal beam. The coupling lenses 232 amay be convex lenses, Fresnel lenses, aspheric lenses, GRIN lenses,etc., as needed. In the following example, a four-channel optical signalis discussed. Four single-channel optical signal beams are outputtedfrom the wavelength division multiplexer 213 and directly enter, inparallel, the respective coupling lenses 232 a of the focusing lens 232.After passing through the coupling lenses 232 a, the four single-channeloptical signal beams are still outputted in parallel to each other, andare respectively focused on the respective photodetectors in thephotodetector array 222. In this structure, the gap between adjacentsingle-channel optical signal beams is relatively large, thuseffectively reducing crosstalk between the channels of a high-speedsignal.

In this example embodiment, the mounting block 231 includes a lens slotand a reflection slot. The focusing lens 232 is disposed in the lensslot, and the optical path shifter 233 is disposed in the reflectionslot. As illustrated in FIG. 4 and FIG. 5, the coupling lenses 232 a ofthe focusing lens 232 are formed as an integrated structure, and thisstructure and the optical path shifter 233 are installed separately onthe mounting block 231. The optical path shifter 233 has a reflectivesurface 233 a. The focusing lens 232 and the optical path shifter 233may also be formed as an integrated single structure. Alternatively, thefocusing lens 232, the optical path shifter 233, and the mounting block231 may be made as an integrated structure.

Example Embodiment 2

FIG. 6 is an exploded-view diagram illustrating a structure of areceiver optical assembly 200 according to a second embodiment of thepresent disclosure. FIG. 7 is a structural diagram illustrating a focalreducing lens array according to the second embodiment. As illustratedin FIG. 6 and FIG. 7, the second example embodiment differs from thefirst example embodiment in that a focal reducing lens array 223 isadded between the focusing lens 232 and the photodetector array 222. Thefocal reducing lenses 223 a of the focal reducing lens array 223 have aone-to-one correspondence with the photodetectors of the photodetectorarray 222. The focal length of each focal reducing lens 223 a is lessthan the focal length of the focusing lens 232, thus shortening theeffective focal length of the focusing system (e.g., the combination ofthe focusing lens 232 and the focal reducing lens array 223). In thismanner, even when the focusing lens 232 or the optical path shifter 233deviates within a certain distance from the main optical axis, thefocusing system can still converge the optical signal on aphotosensitive area of the photodetector array 222, thus improving thedegree of tolerance to the incident light angle and aperture deviation.As a result, the assembly tolerance of a focusing lens array, theoptical path shifter, or other optical assemblies is relaxed, and theaccuracy requirement for assembling an optical assembly is lowered,facilitating production and assembly, improving production efficiency,and lowering costs.

The focal reducing lens array 223 of this example embodiment is formedas a single structure. Alternatively, the focal reducing lens array 223may also be made as a structure in which the focal reducing lenses 223 aare separate from one another.

Example Embodiment 3

FIG. 8 is an exploded-view diagram illustrating a structure of areceiver optical assembly 300 according to a third embodiment of thepresent disclosure. As illustrated in FIG. 8, the third exampleembodiment differs from the second example embodiment in that thefocusing lens 232 is disposed on the optical path after the optical pathshifter 233. In the following example, a four-channel optical signal isdiscussed. Four single-channel optical signal beams are outputted fromthe wavelength division multiplexer 213 and enter, in parallel, theoptical path shifter 233. After being reflected through the reflectivesurface 233 a of the optical path shifter 233, the single-channeloptical signal beams enter, in parallel, the coupling lenses 232 a ofthe focusing lens 232. After passing through the coupling lenses 232 a,each of the single-channel optical signal beams is focused on itsrespective photodetector in the photodetector array 222. Alternatively,each of the single-channel optical signal beams is focused on itsrespective photodetector after passing through the corresponding focalreducing lens of the focal reducing lens array 223. During actual use,the focusing lens 232 may be selected to be disposed on the optical pathbefore or after the optical path shifter 233 in accordance with theneeds of the optical path.

In this example embodiment, the optical path shifter 233 and themounting block 231 are made as an integrated structure, and then thefocusing lens 232 is adhered onto a light outputting end surface of theoptical path shifter 233. Alternatively, the optical path shifter 233,the mounting block 231, and the focusing lens 232 may also be made as anintegrated structure. Still alternatively, the shape of the mountingblock is not limited and may also have other variations.

In each of the aforementioned example embodiments, the reflectivesurface 233 a of the optical path shifter 233 and the optical axis ofthe focusing lens 232 have an angle of inclination, which may bearranged between 40° and 50°. An optimal angle may be approximately 45°,such as 43°, 48°, etc., so that the receiving system may have lowerreturn loss.

Example Embodiment 4

The present disclosure further provides an assembly method for theaforementioned receiver optical assembly, the method including thefollowing steps.

First, as illustrated in FIG. 3, the receiver optical port 212 and thewavelength division multiplexer 213 are installed on the opticalplatform 211 to form the first assembly 21. The photodetector array 222is installed on the circuit board 221 to form the second assembly 22.The focusing lens 232 and the optical path shifter 233 are installed onthe mounting block 231 to form the third assembly 23.

Next, the aforementioned first assembly 21 and second assembly 22 areinstalled inside the housing 10.

Then, the photodetector array 222 is covered with the aforementionedthird assembly 23, and the position of the third assembly 23 is adjustedso that an optical signal outputted from the wavelength divisionmultiplexer 213 is coupled to the photodetector array 222.

Finally, the third assembly 23 is fixed on the circuit board 221.

As illustrated in FIG. 6, in another example embodiment, the secondassembly 22 further includes the focal reducing lens array 223 installedabove the photodetector array 222. Thus, the step of installing thephotodetector array 222 on the circuit board 221 to form the secondassembly 22 further includes installing the focal reducing lens array223 above the photodetector array 222. The focal reducing lenses of thefocal reducing lens array 223 have a one-to-one correspondence with thephotodetectors of the photodetector array 222. The focal length of eachfocal reducing lens is less than the focal length of the focusing lens232.

The aforementioned method for fixing the third assembly 23 on thecircuit board 221 includes connecting the circuit board 221 to themounting block 231 of the third assembly 23 by means of glue and fixingthe third assembly 23 on the circuit board 221 by means of the mountingblock 231 so that the optical signal beams are coupled to thephotodetectors of the photodetector array 222 after passing through thefocusing lens 232 and the optical path shifter 233. Other methods forfixing and connecting may be used between the mounting block 231 and thecircuit board 221.

None of the aforementioned steps for forming the first assembly 21, thesecond assembly 22, and the third assembly 23 restricts the order of theassembly sequence, and the three assemblies may be separately assembledat the same time into semi-finished products for later use. When thereceiver optical assembly is being assembled, the first assembly 21 andthe second assembly 22 are first installed in the housing in accordancewith their preset positions, and then the front and back portions of theoptical path are coupled by means of adjusting the third assembly 23,thus effectively improving coupling efficiency, enabling convenientadjustment of the position of the aforementioned assembly by means ofgrasping the mounting block, increasing the operability of the couplingand assembly, effectively improving assembly efficiency, and loweringcosts.

In the embodiments of the present disclosure, a focusing lens and anoptical path shifter are integrated to form an assembly, and the frontand back portions of the optical path are coupled by means of adjustingthis assembly, thus effectively improving coupling efficiency. Inaddition, a mounting block is added so that the position of theaforementioned assembly is conveniently adjusted by means of graspingthe mounting block, thus increasing the operability of the coupling andassembly and effectively improving assembly efficiency.

The series of detailed descriptions above is only intended to providespecific descriptions of feasible embodiments of the presentapplication. They are not to be construed as limiting the scope ofprotection for the present application; all equivalent embodiments orchanges that are not detached from the techniques of the presentapplication in essence should fall under the scope of protection of thepresent application.

What is claimed is:
 1. A receiver optical assembly, comprising: anoptical platform, a receiver optical port and a wavelength divisionmultiplexer being arranged along an optical path on the opticalplatform; a circuit board, a photodetector array being disposed on thecircuit board; and a mounting block, a focusing lens and an optical pathshifter being disposed on the mounting block, the mounting block beingseparated from the optical platform and fixed on the circuit board, andthe optical path shifter being placed above the photodetector array,wherein incident light containing a multi-channel optical signal entersthrough the receiver optical port, the wavelength division multiplexerdivides the incident light into a plurality of single-channel opticalsignal beams, and the single-channel optical signal beams are coupled tophotodetectors on the photodetector array after passing through thefocusing lens and the optical path shifter on the mounting block.
 2. Thereceiver optical assembly of claim 1, wherein the mounting blockcomprises a supporting portion, the mounting block being fixed on thecircuit board by means of the supporting portion.
 3. The receiveroptical assembly of claim 2, wherein the focusing lens and the opticalpath shifter are formed as an integrated structure.
 4. The receiveroptical assembly of claim 2, wherein the mounting block comprises a lensslot and a reflection slot, the focusing lens being disposed in the lensslot and the optical path shifter being disposed in the reflection slot.5. The receiver optical assembly of claim 2, wherein the focusing lens,optical path shifter, and the mounting block are formed as an integratedstructure.
 6. The receiver optical assembly of claim 1, wherein a focalreducing lens array is disposed above the photodetector array, focalreducing lenses of the focal reducing lens array having a one-to-onecorrespondence with photodetectors of the photodetector array, and thefocal length of each focal reducing lens being less than the focallength of the focusing lens.
 7. The receiver optical assembly of claim6, wherein the focusing lens comprises a plurality of coupling lensesthat are each positioned along the optical path of its respectivesingle-channel optical signal beam.
 8. An assembly method for a receiveroptical assembly, comprising: installing a receiver optical port and awavelength division multiplexer on an optical platform to form a firstassembly; installing a photodetector array on a circuit board to form asecond assembly; installing a focusing lens and an optical path shifteron a mounting block to form a third assembly; installing the firstassembly and second assembly inside a housing; covering thephotodetector array with the third assembly and adjusting the positionof the third assembly so that an optical signal outputted from thewavelength division multiplexer is coupled to the photodetector array;and fixing the third assembly on the circuit board.
 9. The assemblymethod of claim 8, wherein the installing a photodetector array on acircuit board to form a second assembly further comprises: installing afocal reducing lens array above the photodetector array, focal reducinglenses of the focal reducing lens array having a one-to-onecorrespondence with photodetectors of the photodetector array, and thefocal length of each focal reducing lens being less than the focallength of the focusing lens.
 10. The assembly method of claim 8, whereinthe fixing of the third assembly on the circuit board comprisesconnecting the circuit board to the mounting block of the third assemblyby means of glue.